“Sure, we can have a regular bear market. That is always the case. But the BIG ONE? I doubt it,” he wrote. “Looking to 2016, we can agree that uncertainties are above average.”

Although there is no evidence of a growing market bubble, which precedes a major market collapse, Grantham admitted to “feeling nervous” for this year’s equity outlook in the U.S.

Grantham defines “bubble” as the S&P 500 advancing to near 2,300. That’s about 25% above the index’s current level.

Grantham said he thinks that in 2015, the Fed approximately offset the year’s “three very large negatives: China, oil, and declining margins, which together caused disappointing global growth.”

China recorded a growth rate of 6.9% last year, contributing more than 25% of global economic growth. The world’s second-largest economy was outpaced by the Indian economy, which grew 7.5% in 2015, official figures showed on Monday.

Oil prices have plummeted from above $100.00 a barrel in mid-summer 2014 to trade around $30.00 this month.

Grantham said he still believes that “with the help of the Fed and its allies, the U.S. market will rally once again to become a fully-fledged bubble before it breaks… That is, after all, the logical outcome of a Fed policy that stimulates and overestimates some more until, finally, some strut in the complicated economic structure snaps.”